Process of scouring and bleaching dyed and undyed cellulose textiles



QLHHUH l \v V." 21-109 SR FIPSZIU? GR 392811262 Oct 25, 1966 E. HELMIPROCESS OF scounme A s Aa i'me DYED 3'281202 AND UNDYED CELLULOSETEXTILES Filed Oct. 10, 1962 DYED OR UNDYED COTTON OR LINEN CLOTH DESIZE7 o 27 ALKA -l SCOUR -TEMF: I60 TO 250F CONCENTRATION .l 0 0 BY wt OFSOLUTION m ce; 02 NaOH TIME MIN. TO 2 HRS.

CONCENTRATION o.I% To|.3% OH 7 -PH 9 TO .5

BY wT. 0F SOLUTlON QUEOUS o TEMI. AMBIENT o F) WASH TIME a To Is MIL.

HYPOCHLORITE BLEACH To F CONCENTRATON 03% To }--NQOCI TIMI-: HR. ToZHRS.

3.15% BY wT. 0F soLuTIoN 9 To 2 50 To I TIME 5 To MIN. BY WT. OFSOLUTION Nausoa I 1 o 5 TEMR AMBIENT (70) WASH --TIME 3 TO l5 MIN.

PEROXIDE BLEACH TEMR 70F To 250F ONCENTRATION a TOIA- o TEMR I-: TO IF.WASH --TlME ?3TOI5 MIN.

0 TEME AMBIENT F) WASH TIME 31'015 IN.

FINISHED CLOTH INVENTORS lV/ZA/IM 1F. Ian/(kw IV/ZZ/IM xx (MP5? UnitedStates Patent 3,281,202 PROCESS OF SCOURING AND BLEACIHNG DYED ANDUNDYED CELLULOSE TEXTILES William E. Helmick, Doylestown, Ohio, andWilliam H.

Cooper, Pensacola, Fla., assignors to Pittsburgh Plate Glass Company,Allegheny County, Pa., a corporation of Pennsylvania Filed Oct. 10,1962, Ser. No. 229,681 9 Claims. (Cl. 8-109) This application is acontinuation-in-part of our copending application Serial No. 65,862filed October 28, 1960 and now abandoned.

The present invention relates to the treatment of textiles. Moreparticularly, the present invention relates to the bleaching of bastfibers and cloth made from these fibers, such as linen. In addition, thepresent invention relates to the bleaching of cotton and linen clothcontaining colored ingrain patterns and/or stripes.

In the bleaching of linen cloth and fibers, it is a most difficultproblem to acquire adequate brightness of the material treated withoutseriously interfering with other desirable qualities of the cloth orfiber treated. Thus, frequently, high brightness achieved duringbleaching results in fiber or cloth having tensile strengthsconsiderably below accepted standards. In addition, it is often foundthat the acquisition of suitable tensile strength in a bleached linenfiber or cloth results in the concurrent production of a cloth or fiberhaving inadequate brightness qualities. Still further, in the bleachingof cellulosic goods such as cotton and linen goods that contain portionswhich have been dyed with dyes not completely fast to conventionalperoxide bleaching solutions, as for instance, naphthol, indigo,anthraquinoid and other similar dyes, bleaching processes which achieveadequate degrees of brightness for commercial standards result in thebleeding of this predyed stripe or pattern. Processes involvingbleaching linen cloth also require bleaching sequences which are quitetime consuming, often necessitating operations lasting forty hours ormore.

In accordance with the present discovery, many of these diflicultiesfacing the prior art have been eliminated. Thus, linen cloth and fiberstreated in accordance with the teachings of this invention are found toattain exceptionally high degrees of brightness while maintainingtensile strengths well within accepted standards. Similarly, cotton andlinen materials containing predyed striping or patterns with dyes notfast to usual peroxide bleaching solutions, are now capable of beingbleached to a high degree of brightness while maintaining adequatetensile strength and with considerably less bleeding of the dyeoccurring. Still further, when applied to the treatment of linen cloth,absorbency of the finished product is considerably improved, thusrendering the process extremely desirable in applications involvinglinen toweling. In addition, substantial reductions in the time requiredto bleach linen cloth are readily achieved.

According to the present invention, linen cloth which has been treatedby conventional desizing operations is passed through two alkaline bathswhich scour and bleach the goods. After the second alkaline treatment,the goods are soured with a sodium bisulfite solution and then treatedin a hydrogen peroxide bleaching bath. The sequential treatment of thelinen cloth in two alkaline baths and the final hydrogen peroxidebleaching solution gives rise to linen material having exceptionallyhigh degrees of brightness and good tensile strength. It is found thatlinen goods treated in this manner also attain absorbent qualities notusually found in linen materials having tensile strengths on the orderof thosefound in material treated in this manner.

In the sequential alkaline bath treatments, the goods 3,281,202 PatentedOct. 25, 1966 are subjected in the first bath to an alkaline solutioncontaining small quantities of ammonium hydroxide. The alkaline solutionis an aqueous solution of sodium carbonate or sodium hydroxide or acombination of the two. In this bath the goods are boiled for periods oftime ranging from fifteen minutes upwards. After completion of theinitial boiling step, the goods are passed to a hypochlorite bleachingbath maintained at a pH of 9 to 12. Treatment in this latter bath isusually conducted at room temperature and for a period of time rangingfrom onehalf hour upwards. After completion of the hypochloritebleaching step, the goods are passed into a bath containing sodiumbisulfite and maintained in an acid pH range of between 1 and 5. Fromthis sodium bisulfite solution, the goods are passed into a hydrogenperoxide bleaching tank where they are bleached to final whiteness.

For a more complete understanding of the present invention, reference ismade to the flow sheet and the following details which describe in amore precise manner the various conditions to be employed in the washingand treating steps of the instant process.

The desizing of the cotton and/ or linen cloth treated may be conductedin any conventional enzyme desizing solution such as, for example, anamylase enzymatic bath. Baths of this kind and the treatment stepsutilized to accomplish desizing are well known in the art and exemplarybaths and treatments are described in Chemistry and Chemical Technologyof Cotton, edited by Kyle Ward, in, published by IntersciencePublishers, Inc., N.Y. 1955, pages 134 through 144. Upon completion ofthe desizing operation, the cloth is subjected to an aqueous wash inwarm water at a temperature in the range of from F. to F; for periodsfrom three to fifteen minutes. Upon completion of the washing operation,the cloth is then introduced into the first stage of the bleachingprocess comprising the instant invention.

The first alkaline treatment the cloth is subjected to involves thecontact of the cloth with an aqueous alkaline solution of sodiumcarbonate or sodium hydroxide containing ammonium hydroxide. The sodiumcarbonate or sodium hydroxide concentration in this aqueous alkalinesolution is usually maintained below 2 percent by weight of solution.Normally, the sodium carbonate or sodium hydroxide concentration of thesolution is about 0.5 percent by weight, but may range broadly frombetween 0.1 percent up to about 2 percent. Ammonium hydroxideconcentrations in the alkaline bath are maintained in a range of from0.1 percent up to 1.3 percent. Generally, the ammonium hydroxideconcentration is maintained somewhere between 0.8 percent and 1.1percent by weight. During the treatment conducted in the aqueousalkaline solution containing ammonium hydroxide, the aqueous solution ismaintained at a pH in the range of between 9 and 11.5. Temperatures ofthe solution are maintained on the warm side and range generally between160 F. to 250 F. The lengths of time the cloth is maintained in contactwith the solution may be varied somewhat, but generally is betweenfifteen minutes to two hours. During the contact of the cloth with theaqueous alkaline solution, the cloth is essentially saturated withsolution. Material after treatment in the aqueous alkaline bath isremoved and washed in a cold water wash for a period of from three tofifteen minutes.

After the washing step, the goods are then introduced into ahypochlorite bleaching tank. The hypochlorite bleaching tank contains anaqueous solution of hypochlorite, usually sodium hypochlorite, butalkaline earth metal hypochlorites may also be employed if desired.Preferably, sodium hypochlorite is utilized in this bleaching bath. Thehypochlorite concentration in the aqueous hypochlorite bleaching bath ismaintained in a range of from 3 to 30 grams per liter hypochloritemeasured as available chlorine. Stated in another way, the hypochloriteconcentration in the aqueous hypochlorite bleaching solution ismaintained in a range of from 0.31 to 3.15 percent by weight. Duringcontact and treatment in the hypochlorite bleaching bath, the goods aremaintained for periods of time ranging between thirty minutes and twohours, and at temperatures ranging broadly between 50 F. to 150 F.Preferably, the temperature of the hypochlorite bleaching tank ismaintained somewhere between 65 F. and 95 F. The goods in thehypochlorite bleaching tank are essentially saturated with thehypochlorite solution.

Goods, after treatment in the hypochlorite tank, are passed into asouring tank containing sodium bisulfite in concentrations ranging from0.1 percent by weight of solution up to 1 percent by weight of solution.The souring conducted in the sodium bisulfite aqueous solution isusually conducted at room temperatures, but the temperature may varybetween 50 F. to 120 F. Treatment in this batch is usually quite shortand ranges anywhere from five minutes to one-half hour. Upon completionof the souring in the sodium bisulfite souring bath, the goods arewashed in cold water usually at ambient temperatures for periods of fromthree to fifteen minutes.

Upon completion of this latter wash, the goods are then introduced intoan aqueous hydrogen peroxide bleaching solution having a pH between 8.5and 11 containing between 0.2 and 1.4 percent by weight of hydrogenperoxide (anhydrous) basis the weight of the aqueous solution. Alsopresent in the hydrogen peroxide bleaching solution are small quantitiesof sodium silicate. Sodium silicates which may be employed have thegeneral formula Na O(SiO where x represents a number from 2 to 4. Theconcentration of the sodium silicate contained in the hydrogen peroxidebleaching bath is in a range generally between 0.1 and 2.0 percent byweight of solution. Temperatures in the hydrogen peroxide bleaching bathare maintained generally between 70 F. and 250 F., but are usuallymaintained within the range of between 60 F. to 185 F. The goods aretreated in the hydrogen peroxide bleaching bath for periods of timeranging between one hour and three hours.

Upon completion of the bleaching cycle in the hydrogen peroxidebleaching bath, the goods are subjected to a double wash, the initialwash consisting of a warm water wash at temperatures from 90 F. to 140F. for periods of between three and fifteen minutes. Upon completion ofthe warm water wash, the goods are then passed into a cold water washtank and subjected to cold water washing at ambient temperatures of 70F. for periods of from three to fifteen minutes. Upon completion of thefinal cold water wash, the goods are then ready for drying, pressing andfinal processing.

For more complete understanding of the present invention, reference ismade to the following examples which are indicative of the modes ofoperation which may be employed in conducting the process of the instantinvention.

EXAMPLE I A desized piece of linen sheeting having a colored in grainpattern was placed in a scouring bath containing 3.74 liters ofsolution, having 1.5 percent NH OH by weight, 1 percent Na CO by weight,and 0.1 percent Sandopan DTC (a sulfonated alcohol wetting agentmanufactured under the trade name Sandopan DTC by the Sandoz ChemicalCorporation, Incorporated). The scouring bath was contained in alaboratory apparatus designed to simulate a commercial jig. The linenmaterial was rotated continuously in the jig and was padded on thereturn side of the cycle and run at 200 F. for a period of thirtyminutes. Upon completion of the thirty minute contact of the solutionwith the cloth, the solution was discharged from the machine and thematerial washed with cold water at ambient temperature (70 F.).

A second aqueous solution of a 3.75 liter volume was prepared andcontained 1.5 percent NaOCl by Weight. The solution was introduced intothe jig and the material rotated as before for a period of one hour atF. Upon completion of this treatment, the solution was discharged andthe material rinsed with cold water at 70 F.

A third solution of 3.74 liters volume was made up containing 0.1percent sodium bisulfite by weight of solution. This solution wasintroduced into the apparatus and contacted with the cloth containedtherein for a period of ten minutes at 70 F. Upon completion of thisstep, the solution was discharged from the apparatus and the materialgiven a rinse in cold water at 70 F. A final aqueous solution of 3.74liters by volume and containing 2 percent H 0 (35 percent) and 0.5percent Na SiO was placed in the apparatus. The material was rotatedwith the solution at 180 F. for a period of two hours. This solution wasthen discharged and the material washed with hot water at F. for aperiod of five minutes, and washed a second time with a cold water washat 70 F. for a further period of five minutes. The material treated wasdesignated as Sample No. 1.

EXAMPLE II Utilizing the procedure of Example I and the solutions, timesand temperatures remaining the same, a piece of cotton sheeting having acolored ingrain pattern was placed in the laboratory apparatus andsubjected to the same treatment as the linen cloth of Example I. Thecloth so treated was designated as Sample No. 1A.

EXAMPLE III Utilizing the solutions identical with those prepared inExample I, a sample of linen sheeting having a colored ingrain patternand a sample of cotton sheeting having a colored ingrain pattern weresubjected individually to the identical bleaching sequence of Example I,but all operations were conducted in a Gaston County Package dyeingmachine. The linen sample obtained in this example was designated No. 2and the cotton sample was designated No. 2A.

The samples obtained from Examples I, II and III were subjected uponcompletion of the bleaching steps to tests for brightness, absorbencyand tensile strength. Brightness was determined with a Huntermultipurpose reflectorneter. Absorbency was measured by dropping a dropof water from a pipe held 2 inches from the surface of the unstretchedcloth. The time required for the disappearance of the specularreflectance from a drop, as visually observed, is a measure of theabsorbency.

Table I Reflectance Tensile Absorbency, Sample No Blue Strength, soc.

lbs/in.

No bleeding of the colored ingrain pattern was observed in the finishedproduct.

EXAMPLE IV A desized piece of linen sheeting having a colored ingrainpattern is placed in a scouring bath containing 3.74 liters of solution,having 1.5 percent NH OH by weight, 1 percent NaOH by weight and 0.1percent by weight Sandopan DTC (a sulfonated alcohol wetting agentmanufactured under the trade name Sandopan DTC by the Sandoz ChemicalCorporation, Incorporated). The scouring bath is contained in alaboratory apparatus designed to simulate a commercial jig. The linenmaterial is rotated continuously in the jig and is padded on the returnside of the cycle and is run at 200 F. for a period of 30 minutes. Uponcompletion of the thirty minute contact of the linen with the solution,the solution is discharged from the machine and the linen material isthen washed with cold water at ambient temperature (70 F).

A second aqueous solution of 3.75 liters volume is prepared containing1.5 percent NaOCl by weight. The solution is introduced into the jig andthe material is rotated as before fora period of one hour at 95 F. Uponcompletion of this treatment, the solution is discharged and thematerial is rinsed with cold water at ambient temperature (70 F.).

A third solution of 3.74 liters volume is made up containing 0.1 percentsodium bisulfite by weight. This solution is introduced into theapparatus and is contacted with the cloth contained therein for a periodof ten minutes at 70 F. Upon completion of this step, the solution isdischarged from the apparatus and the material is given a rinse in coldwater at 70 F.

A final aqueous solution of 3.74 liters by volume and containing 2percent H 0 (35 percent by weight) and 0.5 percent Na Si-O is placed inthe apparatus. The material is rotated with the solution at 180 F. for aperiod of two hours. This solution is then discharged and the materialis washed with hot water at 140 F. for

a period of five minutes and is washed a second time with a cold waterwash at 70 F. for a further period of five minutes.

After drying the treated linen is tested for brightness and absorbency.The cloth is found to' have a high reflectance in excess of 84 asmeasured on a Hunter refiectometer and an absorbency of 1 second. Nobleeding of the colored ingrain pattern is observed.

As can be readily seen from the above table, linen cloth treated in themanner outlined hereinabove attains and sustains a high degree ofbrightness with very good tensile strength. In addition, cotton clothtreated in the above manner also is adequately bleached while attainingadequate tensile strength and good absorbency.

While the invention has been described with reference to cotton andlinen goods composed essentially of cotton or linen fibers, it is .ofcourse to be understood that goods treated are intended to includefabrics and cloths which are composed of mixtures of cotton fibersand/or linen fibers with other fibers such as wool, rayon, nylon, andother synthetic and natural fibrous materials easily blended with cottonand/or linen. Cloth unions, as contemplated generally, contain at least15% by weight of cotton and/ or linen therein, and include cloth whichhas been woven as well as knitted cloth.

While the invention has been described with reference to certainspecific examples, it is not intended to be so limited except insofar asappears in the accompanying claims.

We claim:

1. A method for bleaching textiles of the group consisting of cotton andlinen comprising scouring the textiles in an aqueous solution of from0.1 to about 2.0 percent by weight of the solution of a member selectedfrom the group consisting of sodium carbonate and sodium hydroxide, andammonium hydroxide in a concentration of from 0.1 to 1.3 percent byweight of the solution, having a pH of between 9 and 11.5, at atemperature of between 160 F. to 250 F. for fifteen minutes to twohours, washing the scoured textiles with water, partially bleaching thewashed textiles in an aqueous solution of sodium hypochlorite having apH of between 9 and 12, at a temperature of between 50 F. to 150 F. forbetween one half hour to two hours, souring the partially bleachedtextiles with an aqueous solution of sodium bisulfite having a pH of between 1 to 5, at a temperature between 50 F. to F. for between five tothirty minutes, washing the textiles from the bisulfite sour in water,and bleaching the washed textiles in an aqueous solution of hydrogenperoxide having a pH of between 8.5 to 11, at temperaturesof between 70F. to 250 F. for between one to three hours.

2. The method of claim 1, wherein the sodium carbon ate concentration ofthe aqueous scouring solution is about 0.5 percent by weight and theammonium hydroxide concentration of said solution is between 0.8 and 1.1percent by weight.

3. The method of claim 2, wherein the aqueous hydrogen peroxide solutioncontains between 0.2 and 1.4 percent H O by weight of solution.

4. The method of claim 1, wherein said textiles are scoured with anaqueous solution of sodium hydroxideand ammonium hydroxide.

5. The method of claim 4, wherein the sodium hydroxide concentration ofthe aqueous scouring solution is about 0.5 percent by weight and theammonium hydroxide concentration of said solution is between 0.8 and 1.1percent by weight.

6. The method of claim 3, wherein the aqueous so dium hypochloritesolution contains below 2.5 percent by weight sodium hypochlorite.

7. A method of bleaching textiles containing fibers selected from thegroup consisting of cotton and linen comprising contacting said fiberswith an aqueous solution of from 0.1 to about 2.0 percent by weight ofthe solution of a member of the group consisting of sodium carbon-ateand sodium hydroxide, said solution containing ammonium hydroxide in aconcentration of from 0.1 to 1.3 percent by weight of the solution andbeing at a pH of between 9 and 11.5 and at temperatures of between F. to250 F., partially bleaching the fibers after said cont act with analkaline solution of sodium hypochlorite having a pH of between 9 and12, souring the partially bleached fibers with an aqueous bisulfitesolution having a pH between 1 to 5, and contacting the bisulfitetreated fibers with an aqueous solution of hydrogen peroxide having -apH between 8.5 and 11.

8. A method of treating textiles containing fibers of the groupconsisting of cotton and linen and having dyed portions which bleed inperoxide bleaching solutions comprising contacting said textiles with anaqueous solution of from 0.1 to about 2.0 percent by weight of thesolution of a member selected from the group consisting of sodiumcarbonate and ammonium hydroxide in a concentration of from 0.1 to 1.3percent by weight of the solution at a pH of between 9 and 11.5 and attemperatures between 160 F. to 250 F., partially bleaching the textilesafter said contact with an alkaline solution of sodium hypochlorite at apH of between 9 and 12, souring the partially bleached textiles with anaqueous bisulfite solution having a pH between 1 to 5, and contactingthe bisulfite treated goods with an aqueous solution of hydrogenperoxide at a pH of between 8.5 and 11.

9. The method of claim 8 wherein said textiles are scoured with anaqueous solution of sodium hydroxide and ammonium hydroxide.

References Cited by the Examiner I UNITED STATES PATENTS 2,020,437 11/1935 Smith 8109 2,202,332 5/ 1940 Butterworth 8-108 2,202,335 5/ 1940Butterworth et a1 8- 109 2,334,066 11/ 1943 Campbell et al.

2,366,740 1/1945 'McEwen 8-1ll 2,903 ,327 9/1959 Rogers '8-108 3,030,1714/1962 Lindsay 81 11 X 3,077,372 2/ 1963 Smolens et al. 8-l 11 X (Otherreferences on following page) 7 FOREIGN PATENTS 945,494 11/1948 France.952,514 5/1949 France.

OTHER REFERENCES 5 An Introduction to Textile Bleaching, I. T. Marsh,Second Impression, 1948, pages 156, 1 8519'3, 197199, 228, 229 and262-267, Chapman and Hall, Ltd., London, England.

Bleaching and Related Processes, J. Merritt Matthews, 10

8 page 572, 1921, The Chemical Catalog Co., Inc., New York, NY.

Fox, M. R.: Vat Dyestuffs and Vat Dyeing, 1947, pages 52 and 53.

Marsh, J. T.: An Introduction to Tex-tile Bleaching, Second Impression,1948, page 270.

NORMAN G. TORCHIN, Primary Examiner.

H. WOLMAN, Assistant Examiner.

7. A METHOD OF BLEACHING TEXTILES CONTAINING FIBERS SELECTED FROM THEGROUP CONSISTNG OF COTTON AND LINEN COMPRISING CONTACTING SAID FIBERSWITH AN AQUEOUS SOLUTION OF FRM 0.1 TO ABOUT 2.0 PERCENT BY WEIGHT OFTHE SOLUTION OF A MEMBER OF THE GROUP CONSISTING OF SODIUM CARBONATE ANDSODIUM HYDROXIDE, SAID SOLUTION CONTAINING AMMONIUM HYDROXIDE IN ACONCENTRATION OF FROM 0.1 TO 1.3 PERCENT BY WEIGHT OF THE SOLUTION ANDBEING AT A PH OF BETWEEN 9 AND 11.5 AND AT TEMPERATURES OF BETWEEN 160*F. TO 250* F., PARTIALLY BLEACHING THE FIBERS AFTER SAID CONTACT WITH ANALKALINE SOLUTION OF SODIUM HYPOCHLORITE HAVING PH OF BETWEEN 9 AND 12,SOURING THE PARTIALLY BLEACHED
 8. A METHOD OF TREATING TEXTILESCONTAINING FIBERS OF THE GROUP CONSISTING OF COTTON AND LINEN AND HAVINGDYED PORTIONS WHICH BLEED IN PEROXIDE BLEACHING SOLUTIONS COMPRISINGCONTACTING SAID TEXTILES WITH AN AQUEOUS SOLUTION OF FROM 0.1 TO ABOUT2.0 PERCENT BY WEIGHT OF THE SOLUTION OF A MEMBER SELECTED FROM THEGROUP CONSISTING OF SODIUM CARBONATE AND AMMONIUM HYDROXIDE IN ACONCENTRATION OF FROM 0.1 TO 1.3 PERCENT BY WEIGHT OF THE SOLUTION AT APH OF BETWEEN 9 AND 11,5 AND AT TEMPERATURES BETWEEN 160* F. TO 250* F.,PARTIALLY BLEACHING THE TEXTILES AFTER SAID CONTACT WITH AN ALKALINESOLUTION OF SODIUM HYPOCHLORITE AT A PH OF BETWEEN 9 AND 12, SOURING THEPARTIALLY BLEACHED TEXTILES WITH AN AQUEOUS BISULFITE SOLUTION HAVING APH BETWEEN 1 TO 5, AND CONTACTING THE BISULFITE TREATED GOODS WITH ANAQUEOUS SOLUTION OF HYDROGEN PEROXIDE AT A PH OF BETWEEN 8.5 AND 11.